Aqueous silicone emulsions are used to provide water repellent coatings on various building surfaces. These emulsions are either used directly on the surface, or as additives in coating formulations or paints. Various silicone based components have been formulated into such emulsions. A long standing problem with silicone emulsions based coatings has been to identify storage and dilution stable emulsions that provide waterproof coatings on a variety of surfaces. For example, there are many teachings of silicone emulsions containing silicone resins, alkoxysilanes, and combinations thereof in attempts to balance storage stability with waterproofing action on a variety of surfaces. In general, emulsions of pre-formed silicone resins have good stability, and provide waterproofing on the outermost surface of building materials. However, emulsions of silicone resins often lack sufficient waterproofing abilities on most porous surfaces because of insufficient penetration beyond the surface. This problem may be overcome by using an alkoxysilane in the emulsion. The alkoxysilane after penetrating into various surfaces upon application from the emulsion, can react to form a resinous waterproof coating. However, alkoxysilanes are limited to only those surfaces that will enhance resin formation from the alkoxysilanes (such as alkaline surfaces). Also, emulsions or aqueous based formulations containing alkoxysilanes often have limited storage stability because of the reactivity of the alkoxy groups. Certain combinations of pre-formed silicone resins and alkoxy resins are also known, representing attempts to combine the benefits of each component. However, a need still exists to identify storage and dilution stable silicone emulsions that provide coatings that impart water repellency to a variety of building surfaces. Furthermore, there is a need to identify such emulsions that comply with stringent VOC (Volatile Organic Content) governmental regulations in many regions.
The present inventors have discovered certain aqueous silicone emulsions that are storage and dilution stable, yet provide water repellent coatings on a variety of substrates. The aqueous silicone emulsions may also be considered as low VOC formulations.